It's positive. Had you been looking at the good things that were in your relationship with your ex youd be in trouble lol
What this seems to be is your own mind underlining the thankfulness you arent with the ex. He does need to be remembered sometimes, when times are low with hubby, but thats what this is. No matter what troubles you face daily, you dont have the underlying fact that the ex was simply not the right guy for you.
If the dream repeats still..it could be an idea to consciously remember the imagery and play out a great ending. Something like your husband pulls up in your car....the ex jumps in with him and takes him on a ride. He asks your ex to stay out of your dreaming life and drops him off at a bar to sit at for eternity lol.
By changing the imagery you may find you dream out the altered situation...and he doesnt reoccur in dreams. After all, if he's now sat in that bar then he will be too drunk shortly to move, any attempt at coming over to your dreams will leave him falling over off his chair and slumped in a corner..out of harms way